Ebola virus is an aggressive pathogen that causes a highly lethal hemorrhagic fever syndrome in humans and nonhuman primates. First recognized near the Ebola River valley during an outbreak in Zaire in 1976 (Bowen, E. T. et al. 1977 Lancet 1:571-573: Johnson, K. M. et al. 1977 Lancet 1:569-571), outbreaks have occurred in Africa in the ensuing 27 years, with mortality rates ranging from 50 to 90% (Peters, C. J. and Khan, A. S. 1999 Curr Top Microbiol Immunol 235:85-95; Sanchez, A. et al. 2001 Filoviridae: Marburg and Ebola viruses in Fields Virology, D. M. Knipe and P. M. Howley (eds.), Lippincott, Williams & Wilkins, Philadelphia, Pa., p. 1279-1304). The natural host for Ebola virus is unknown, so it has not been possible to implement programs to control or eliminate viral reservoirs of transmission to human populations. The rapid progression of Ebola virus infection has further complicated the control of this disease, affording little opportunity to develop acquired immunity. There is currently no antiviral therapy or vaccine that is effective against Ebola virus infection in humans.